When an image is captured under controlled lighting, the power of the light source has great impact on the result. All things being equal, brighter sources will send more photons to the sensor during an exposure, producing a brighter and less noisy image.
The brightness of the source, however, is just one way to control the amount of light that reaches the sensor of a computational imaging system. Modern systems use an arrangement of devices to transport light from a source to the scene (or from the scene to sensor) and these devices (galvanometers, digital micro-mirror devices, liquid-crystal panels, phase modulators, etc.) are often programmable. However, these devices in the currently used configurations are also inefficient in their power consumption.
Studies of this problem began in the 1960s for arrangements of just the three main active components; a light source, a controllable light-blocking mask, and a photo-sensor. In this ubiquitous configuration, the light source is always turned on, and, while the energy efficiency of light sources have greatly increased over time, having the light source always turned on is still a major source of power consumption. The controllable light-blocking mask is used to selectively light the scene to be captured by the photo-sensor. This practice is not energy efficient, however, due to the fact that photons that are being generated are simply blocked within the system.